miss fire on #6 cylinder

[my dime]

I just recently replaced all my sparkplugs with iridium s
this morning going to work I stopped at a light and the engine began to run ruff.
autozone says p0306 code #6 cylinder.
would this have happened because of that brand of plugs and if so why just that cylinder?
it has ran fine for A weak now driving it everyday now all of a sudden this.
thanks

 

[blind squirrel]

Is it a v6 or v8? I think I remember reading that the v6's are very sensitive to what brand of plug is used. I would check the torque and verify that the connection is tight on all the plugs.

 

[CookieRoe]

I've never heard of the V6 being "sensitive" to any plugs. That being said, I still don't know why people get the expensive Iridium/Platium/FerryDust spark plugs. Factory calls for copper plugs. The cheap kind. Anyway, 1GRFE was designed for it. Manual says to change them every 30,000 miles. Come to think of it, I THINK I saw that the V6 fowls (burns) them up a bit (the expensive plug), but that doesn't affect it running rough.

Good Luck.

#6 misfire diagnosis is quite often an ominous symptoms of a bad head gasket.

 

[fdbyrne]

The #6 misfire is often the first symptom of the head gasket issue, but this doesn't sound like that. With the head gasket it will usually run rough on startup then even out somewhat. I've not heard anybody say that theirs started at a stop light. I guess it is possible, however.

I've read a number of threads on this forum about the V6 being picky about plugs. I already had the NGK Iridium plugs purchased but chose to buy the regular NGK copper plugs from the dealer after reading about a few guys that had problems.

I'd go to the dealer and buy the right plugs (copper NGKs or Densos) and replace the Iridium ones before I started worrying too much about a bigger problem.

My 30,000 mile cheapo copper NGK/Denso OEM plugs that the factory put in lasted 128,000 miles and weren't causing any problems when I replaced them.

 

[scw1991]

When I purchased my plugs from Toyota for my V6 07', their catalog shows use of copper plugs for 07'. Then for 08'-09' models, iridium is specified if I recall. Or it was iridium starting with the 09' model.....

 

[hearno]

The #6 misfire is often the first symptom of the head gasket issue, but this doesn't sound like that. With the head gasket it will usually run rough on startup then even out somewhat.

Correct but in two years I haven't seen one of these threads not end up in a failed head gasket. Some have switched coils etc and found a temporary "solution" only to have the misfire but come back months later. OP if you have a 2003-2006 V6, might in for a large repair.

 

[fdbyrne]

In the end it may turn out to be the head gasket, but it would be one hell of a coincidence if the very first sign of trouble happened right after the plugs were changed. I'd really have to rule out the plugs and coils before I would really start worrying about a worse case scenario.

OP... keep us posted. Don't forget to followup with a solution when and if you find one.

 

[my dime]

In the end it may turn out to be the head gasket, but it would be one hell of a coincidence if the very first sign of trouble happened right after the plugs were changed. I'd really have to rule out the plugs and coils before I would really start worrying about a worse case scenario.

OP... keep us posted. Don't forget to followup with a solution when and if you find one.

Sorry about that.
it is an 2007 v6
it had the original demso or something like that plugs (they were bad)
I decided on the iridium only because of life span of plugs thats all really.
it had been running fine from saturday week before last until 45 miles after I started it this morning when I came to a red light.
I had a jeep Cherokee once and I was told that they were very finicky about the type of plugs you replaced them with.my concern however was that it was just on cylinder 6 and no other.
thanks guys for your thoughts and opinions.

 

[hearno]

yea if it's an 07, follow the plug issue and don't sweat the HG.

 

[BlackWorksInc]

I've never heard of the V6 being "sensitive" to any plugs. That being said, I still don't know why people get the expensive Iridium/Platium/FerryDust spark plugs. Factory calls for copper plugs. The cheap kind. Anyway, 1GRFE was designed for it. Manual says to change them every 30,000 miles. Come to think of it, I THINK I saw that the V6 fowls (burns) them up a bit (the expensive plug), but that doesn't affect it running rough.

Good Luck.

#6 misfire diagnosis is quite often an ominous symptoms of a bad head gasket.

The only real difference is longevity, some people would rather pay a bit extra not to have to worry about the plugs until 90k rather than 30k. Also Toyotas can be a bit sensitive on plugs, they seem to favor NGK & Denso vs. anything else. Don't know why...

In the end it may turn out to be the head gasket, but it would be one hell of a coincidence if the very first sign of trouble happened right after the plugs were changed. I'd really have to rule out the plugs and coils before I would really start worrying about a worse case scenario.

OP... keep us posted. Don't forget to followup with a solution when and if you find one.

Well it's possible that the plugs were so worn/fouled that the nice new crisp plugs are creating a better flame front (more pressure) which exacerbates the HG issue. Just a thought.

As for the OP...

[MENTION=124622]my dime[/MENTION]

Pull the plug from #6 and inspect it, then swap it with #1 and take the ignition coil from #5 and swap it with #6 (make sure you mark all your coils and plugs so you know where it came from originally.) Then have the DTCs cleared and drive the vehicle, if the MIL comes back you can now point to the issue at hand (if its a P0301 it's the plug, if its a P0305 it's a coil, if it's a P0306 there's a mechanical issue with the cylinder such as a HG, valve, rings, ect.) It is what we do at work when we have intermittent misfires or borderline misfires we are having trouble diagnosing.

 

[my dime]

The only real difference is longevity, some people would rather pay a bit extra not to have to worry about the plugs until 90k rather than 30k. Also Toyotas can be a bit sensitive on plugs, they seem to favor NGK & Denso vs. anything else. Don't know why...



Well it's possible that the plugs were so worn/fouled that the nice new crisp plugs are creating a better flame front (more pressure) which exacerbates the HG issue. Just a thought.

As for the OP...

[MENTION=124622]my dime[/MENTION]

Pull the plug from #6 and inspect it, then swap it with #1 and take the ignition coil from #5 and swap it with #6 (make sure you mark all your coils and plugs so you know where it came from originally.) Then have the DTCs cleared and drive the vehicle, if the MIL comes back you can now point to the issue at hand (if its a P0301 it's the plug, if its a P0305 it's a coil, if it's a P0306 there's a mechanical issue with the cylinder such as a HG, valve, rings, ect.) It is what we do at work when we have intermittent misfires or borderline misfires we are having trouble diagnosing.

Thank you very much for this advice. I will do what you have suggested this weekend and repost what happens.
I installed boch iridium plugs last Saturday and had no problems at all untill this morning.
It just seems to me if it was bad plug or coil etc.it would had acted this way from the beginning.
I suspect the coil or plug.if it is one of the other should I pull boch plugs and install ngk?
thank you.

 

[BlackWorksInc]

Hehe... Eh, Bosch can be a bit finicky in Toyotas from my experience (again, I have no idea... maybe the cars are just racists?)

Try swapping the plugs and coils around for now and see what happens.

 

[Geri O]

Interesting that I just came across this thread.

My girlfriend's 2004 4Runner has 208,000 miles on it and it ha been nearly flawless the entire time (except for that cracked dash thing which we had written off to age, but it looks like that will be taken care of!).

Recently, I drove it to pick up her grandkids and when I started it, I noticed a miss for a minute or two, then it cleared up and ran normally. I asked her if she had (A) ever noticed this and (B) ever had the spark plugs changed. We looked through her service records and it doesn't look like they ever have. Geez! Oh, and this is when she told me that the check engine light came on during her drive home from work, so she pulled in the AutoZone and had them run the diagnostics on it. All it turned up was #6 plug "not working properly". This was all good to know...)

So I bought the proper Denso plugs (Iridium, since they didn't have the copper ones) and installed them. Not too bad, except for the scary feeling of the old plugs backing out. But none of them galled and they all looked the same. Kinda brown with some age, but no oil on them. I used anti-seize compound on the new ones and finished the job easily (and a LOT easier than I thought it would be!). I disconnected the battery to clear the codes, cranked the 4Runner, and all seemed fine.

A week later, she said the check engine light came on again, but when I went to check it, the miss had come back and like last time, it went away after a minute or two. Also, the check engine light had gone off, which was odd.

Anyway, my point of the post is to inquire about something I read earlier. Is there a chance of a head gasket problem? I hope to change the plugs for trouble-shooting purposes early next week, so I'll know more then.

I guess all good things must come to an end. This 4Runner is still running and driving great. It has survived 3 grandkids, 4 road trips with us and them, and her daily commute to work for 10 years. It's the most impressive vehicle I've been around. I'm certain that with these kind of miles, some repairs are on the horizon. And since I just bought a new Nissan Armada I was looking for a 4Runner, But the deal on the Nissan was way too good to pass up. Basically took over some notes), I hope to take some of the load off of the 4Runner from now own.

Thanx for any insight.

 

[iBison]

I had the same thing recently. I really hope your luck is better than mine. Almost $900 in parts and machine work. And FYI Advance Auto has Denso long life plugs for ~$9 trt30 code for 30% off and there is a $3 per rebate on them. Get a set of plugs for ~$18.

Good luck

Coolant in #6, verified before tear down with borescope.

 

[fdbyrne]

Interesting that I just came across this thread.

My girlfriend's 2004 4Runner has 208,000 miles on it and it ha been nearly flawless the entire time (except for that cracked dash thing which we had written off to age, but it looks like that will be taken care of!).

Recently, I drove it to pick up her grandkids and when I started it, I noticed a miss for a minute or two, then it cleared up and ran normally. I asked her if she had (A) ever noticed this and (B) ever had the spark plugs changed. We looked through her service records and it doesn't look like they ever have. Geez! Oh, and this is when she told me that the check engine light came on during her drive home from work, so she pulled in the AutoZone and had them run the diagnostics on it. All it turned up was #6 plug "not working properly". This was all good to know...)

So I bought the proper Denso plugs (Iridium, since they didn't have the copper ones) and installed them. Not too bad, except for the scary feeling of the old plugs backing out. But none of them galled and they all looked the same. Kinda brown with some age, but no oil on them. I used anti-seize compound on the new ones and finished the job easily (and a LOT easier than I thought it would be!). I disconnected the battery to clear the codes, cranked the 4Runner, and all seemed fine.

A week later, she said the check engine light came on again, but when I went to check it, the miss had come back and like last time, it went away after a minute or two. Also, the check engine light had gone off, which was odd.

Anyway, my point of the post is to inquire about something I read earlier. Is there a chance of a head gasket problem? I hope to change the plugs for trouble-shooting purposes early next week, so I'll know more then.

I guess all good things must come to an end. This 4Runner is still running and driving great. It has survived 3 grandkids, 4 road trips with us and them, and her daily commute to work for 10 years. It's the most impressive vehicle I've been around. I'm certain that with these kind of miles, some repairs are on the horizon. And since I just bought a new Nissan Armada I was looking for a 4Runner, But the deal on the Nissan was way too good to pass up. Basically took over some notes), I hope to take some of the load off of the 4Runner from now own.

Thanx for any insight.

I still don't think that the OP's issue is with the head gasket, but I'm afraid that your problem is most likely the head gasket. It's got all the 'normal' indicators and your girlfriend's truck is a 2004 which is much more likely to have a head gasket issue than the OP's 2007.

You're probably looking at a $2500 to $3500 repair. The good news is that it'll probably be fixed for good and give you many more miles afterwards.

 

[fullboogie]

In my short experience with my '08 V6, these engines are extremely picky about plugs. See this thread http://www.toyota-4runner.org/4th-gen-t4rs/195771-engine-woes-all-too-obvious-fix.html because I thought I had the issue resolved with Champion plugs. It came back a few months later, and then I installed Denso plugs and it's all cured.

 

[my dime]

I still don't think that the OP's issue is with the head gasket, but I'm afraid that your problem is most likely the head gasket. It's got all the 'normal' indicators and your girlfriend's truck is a 2004 which is much more likely to have a head gasket issue than the OP's 2007.

You're probably looking at a $2500 to $3500 repair. The good news is that it'll probably be fixed for good and give you many more miles afterwards.

here's the follow up gentlemen..
replaced plugs with boch iridium(thats all the local store had for my 2007 v6) took out the boch fusion Platinum (I thought they were iridium)
And all is fine...instantly.
except that check engine light is on but it no longer has miss fire.
im sure as I drive it comp.will clear it hopefully .
thank s so much for all the help

 

[fullboogie]

here's the follow up gentlemen..
replaced plugs with boch iridium(thats all the local store had for my 2007 v6) took out the boch fusion Platinum (I thought they were iridium)
And all is fine...instantly.
except that check engine light is on but it no longer has miss fire.
im sure as I drive it comp.will clear it hopefully .
thank s so much for all the help

Be forewarned that those Bosch plugs will likely do the same thing. I had the same problem with those plugs before going to the Densos. I'd actually gone through a set of Bosch and a set of Champions before installing the Densos.

 

[Geri O]

I still don't think that the OP's issue is with the head gasket, but I'm afraid that your problem is most likely the head gasket. It's got all the 'normal' indicators and your girlfriend's truck is a 2004 which is much more likely to have a head gasket issue than the OP's 2007.

You're probably looking at a $2500 to $3500 repair. The good news is that it'll probably be fixed for good and give you many more miles afterwards.

Hi, Mr. Byrne (making an assumption there...)), thanx for the response.

We were hopeful on having a successful repair on this truck which has been so good to her. Unfortunately, after a few days of diagnostics with 2 shops and a dealer, it's been determined that the head (yep, on #6 cylinder) is warped beyond planing and repair and the other head is on the fence. We've been told by all ofd the shops that they are scared of making any repairs on this engine, preferring to replace the engine altogether. And we've been quoted everywhere from 8K to 10K for a rebuilt engine with a 3-year warranty. On top of this, no one can put their hands on an engine right away. Between that and this 2004 4Runner still has the original transmission, the G/F's son found her a pristine 2011 4Runner that she bought last night. We will bring home the 2004 and hopefully sell it on Craigslist, although I'm going to look around for a local "good ol' boy" that might be able to drop a used engine in it for a few dollars (they do exist...)). We all agree that she let the 2004 run hot when she was trying to get home with a leaky water pump this last winter. So no one is blaming the truck, although all of the shops agree and tell us, this all-aluminum motor has no tolerance for excessive heat whatsoever. We have absolutely no regrets on this truck, it ran flawlessly for 11 years and 3 grandkids, so it served us very well. Stuff happens, as they say.

 

[fdbyrne]

I'm sorry to hear that.

The numbers that you are being quoted seem pretty ridiculous though. You can buy an entire 2004 1GR-FE engine, completely rebuilt, on eBay for less than $2500 shipped (from a seller with good feedback). You can buy a used head from car-part.com (it's a website that acts as a network for salvage yards nationwide) for $150 to $200.